The TV cable/HDMI "hub" that connects the TV to up to four sources seems to be the issue

The TV cable/HDMI "hub" that connects the TV to up to four sources seems to be the issue

There is a TV "hub" that the cable from the TV plugs into. This hub as I am calling it has four other ports for HDMI cables. I can plug the set top box into it for the cable TV signal. I also have a Roku device that I plug into this hub. At first, I could switch between one HDMI input and the other and go from Spectrum cable TV to the Roku device and back and either worked fine. Now, if I have both sources plugged in, it does not see a source on any of the HDMI inputs. If I have only one or the other, it sees it and it works. So, if I have only the cable TV plugged into the hub, it sees that connection/signal and it works fine. If I have only the Roku plugged into the hub, it sees that connection and works fine. It does not see either when I have both plugged in. Do I simply need a new hub? If so, where can I get hardware that will work for a replacement?